Welder control system



F. H, ROBY Nov. 14, 1939.

WELDER CONTROL SYSTEM Filed July l, 1937 4 Sheets-Sheet l M N T N Wm@ ff,f f7. w l. .l

Nov. 14, 1939. F. H, ROBY 2.179.957

WELDER CONTROL SYSTEM Filed July l, 1937 4 Sheets-Sheet 2 Nov. 14, 1939.F'. H. ROBY 2.179.957

WELDER CONTROL SYSTEM Filed July l, 1957 4 Sheets-Sheet 3 BY J @4% @N lA TTOR/VEV Nov. 14, 1939. F, ROBY 2.179.957

WELDER CONTROL SYSTEM Filed July 1, 1957 4 Sheets-Sheet 4 179 y; 7a /NVEA/TOR ff/Mrmm H.- Fogg.

@il 7% @M A TT ORNE Y Patented Nov. 14, 1939 PATENT OFFICE wELDr-:nCONTROL SYSTEM Frank H). Roby, Milwaukee, Wis., assignor to Square DCompany, Detroit, Mich., a corporation of Michigan Application July 1,1937, Serial No. 151,358

Claims.

This invention relates to a system of electric Welder control and hasfor its primary object the provision of a motor driven repeat timer forelectric welding control and a system employing the same which shall beextremely simple, economical and durable and which shall afford a widerange of welding speeds including very short welding times.

Another object of the present invention is an improved motor drivenWelder timing device which shall obviate the necessity oi' a magneticclutch or other means for picking up the timing contacts.

Another object oi' the invention is to provide an automatic weldercontrol system,utilizing a synchronizing relay which initiates thewelding cycle and which can b'e energized only in a dellnite position oia timing relay.

Another object of the invention is to provide an automatic Weldercontrol system using a motor driven timing relay in which the motor maybe either continuously operated or may be ener-I" gized only with theinitiation of the welding cycle without causing an unduly long weldingtime for the initial welding operation.

Other objects and features of this invention will be readily apparent tothose skilled in the art from the following specification and theappended drawings illustrating certain embodiments of the invention inwhich:

Figure 1 is a iront elevational view of a control panel according to thepresent invention.

v1ilgure2 is aside elevational view of the panel shown in Figure 1.

Figure 3 is a vertical sectional view on the line III-III of Figure 1. l

Figure 4 is a partial horizontal sectional view on the line IV--IV ofFigure 1.

Figure 5 is a schematic wiring diagram for the 40 control panel.

V Flgure is a simpliiied wiring diagram of the -welder control systemslciowing all its component parts. V

Figure 7 is a partial simplified wiring diagram of a modified system.

Figure 8 is a detail section of the panel connection terminals. 4

Figure 9 is a generally diagrammatic view showing the operating parts oia welding machine to which the control system may be applied.

The control panel according to the present invention comprises anexterior supporting or mounting plate I having mounted thereon a ternminal board 2 and a'panel 3 supporting the control elements of thesystem and removably (Cl. 21e-4) mounted with respect to the mountingplate I and the terminal board 2. Upon the panel are mounted atransformer 4, a control relay indicated'generally at 5 and a timingrelay indicated generally at 6. The control relay 5 may be of 5conventional form and its details of construction form no part of thisinvention. It is a magnetically operated relay of the normally open typehaving an operating coil 1 shown only schematically in Figures 5 and 6and is provided 10 with three cooperating sets of contacts 8. 9 and II.

The timing relay 6, as shown in Figures 1 to 4 inclusive, embodies areciprocable insulating rod I2 having mounted thereon spring biasedbridg- 15 -ing contact elements I3, Il, I5 and I6. Each of thesebridging contacts is biased on the rod by means of a compression springI1 disposed about the rod and having its end remote from the bridgingcontact received Within a washer I8 20 pressed against a stop I9 on therod. This construction is duplicated for each of the bridging contactswith the exception of the lowermost contact I6 which is reversed indirection and is closed at the extreme lower position of the rod 25 I2.The rod I2 at its upper end is attached by means of studs 2| within aslot in a member 22 to which is pivotally connected a pair of arms 23 asby means of a pivot pin 24, the arms 23 being rigidly connected by across piece 25 and pivoted 30 at their opposite ends to a base piece 26as by means of a pin 21. 'I'he base piece 26 is rigidly supported on thepanel 3. A stop 28 is rigidly secured to the panel 3 and a compressionspring 29 disposed between the member 22 and the stop 35 23 serves tobias the rod I2 in a downward direction. At its bottom end the rod I2 issimilarly connected to a member 3| pivotally mounted on arms 32 whichare, in turn, pivotally connected to a base piece 33 rigid with thepaneL The bot- 40 tom end oi' the member 3l is provided with a ballbearing roller 34 which bears against the operating surface of a cam 35which is rigidly mounted on a shaft 36 and by its rotation serves toeect reciprocation vo i` the rod I2. The shaft 3G 45 is driven by anelectric motor 31 through a set of reduction gears within the casing 38which may be ofconventional form. The spring elements 39 "(Flgure 2)pass through the pivot pins for'thearms 23 and 32 and serve to insurethe 50 proper rotation of the pins within the bearings provided withinthe members 22 and 3|.

I'he operating motor 31 is herein illustrated as a series wound motorprovided with a poten-'- ,tiometer circuit to 'give variable speedopera- 'Ihis arrangement, in addition to the above stated advantages,also results in a reduction in the percentage of speed change due touctuations in line voltage and gives to the series motor operatingcharacteristics more nearly approaching those of a variable speed,direct current motor of the shunt or compound type.

The timing relay includes a distinct arrange-l ment for varying thepositions of certain of the stationary contacts. Each set of stationarycontacts is mounted upon an insulating block and these are hererepresented in order from the top to the bottom by the numerals 43, 44,45 and 46. Each of the stationary contacts includes a terminal connector41 extending to the left hand side of the blocks 43 to 46 and havingmounted thereagainst posts 48 extending forwardly of the back insulatingblocks. Within the posts 48 are threaded studs 49 bearing contactsurfaces 5I at their lower ends .in the case of the upper three sets of.contacts and at the upper ends in the case of the lowest sets. Nuts 52may be provided for preventing undesired adjustment or movement of thestationary contacts. This arrangement is shown in Figures 1 and 2 and inenlarged form in Figure 4 and provides means not only for mounting thestationary contacts but for providing adjustment for each stationarycontact individually. The end blocks 43 and 44 supporting the sets ofstationary contacts are rigidly secured to the panel 3'by means of studs53 and located in these extreme blocks and extending therebetween areguide rods 54 upon which are slidably mounted the intermediate contactsupporting insulating blocks 44 and 45. Compression springs 55 areprovided between the end and intermediate blocks and serve to bias theblocks 44 and 45 to intermediate positions remote vfrom the blocks 43and 46, Adjustment rods 56 and 51 are provided, the rod 56 being securedto the block 44 by stud 58 and extending slidably through the block 43and provided at its upper end with an adjusting nut 59. The rod 51 istied to the block 45 by means of a stud 6I and extends slidably throughthe blNck 46 and is provided at its lower end with an adjusting nut 62.With this arrangement it is seen that while the stationary contactscooperating with plates I3 and I5 can only be adjusted by means of theirindividual mountings on the blocks 48, means is provided for quick andeasy adjustment of the positions of the stationary contacts cooperatingwith the bridging contacts I4 and I5 by tightening or loosening thestuds 59 and 62 to shorten or extend the rods 56 and 51 and to effectmovement bodily of the contact supporting blocks 44 and 45 and henceprovide for quick and easy individual and separate adjustment of thecontacts cooperating with the bridging contacts plates I4 and I5.

'Ihe panel 3 is supported on the back plate I in spaced relation bymeans of spacer bolts 8| at the corner of the panels over which thepanel 3 is mounted and maintained in rigid supporting relation by thenuts 82 at the front. The terminal board 2 is comprised of a pair ofinsulating blocks 83 and 84 rigidly securedto the front face of the backplate I and having mounted thereon a plurality of terminal connectors 85having connected thereto rigid contact elements 86. C- operating withthe contact elements 86 are contact surfaces 81 mounted on connectors 88on the back face of the panel 3. The connectors 88 are loosely receivedin recesses 89 in an insulating block 9| which is rigidly secured to theback face of the panel 3. 'Ihe connectors 88 are maintained in place bythe engagement of their terminal screws 92 in recesses in the back faceof the panel. Compression springs 93 are provided biasing the contactsurfaces 81 away from the panel 3 and providing contact pressure betweenthe contact elements 86 and the contact surfaces 81 when the panel 3 isin supported relation with the back plate I. The internal Wiring of thecontrol elements mounted on the panel ls connected terminally to theterminal screws 92 on the connectors 88 and the exterior control wiresleading to the various operating and operatedelements exterior to thepanel are connected to the terminal connectors 84. By this means it isseen that upon removal of the nuts 82 the panel 3 and the controlelements supported thereon may be directly removed from the back platefor the replacement of an entire panel and for repair without disturbingthe exterior connections,

The welding control system herein illustrated is intended for operationwith a pneumatically operated Welding tool having an operating valve inthe handle and a check valve in the airline leading to the handle toprevent leakageof air through the operating valve in the welding toolorithe packing gland in the head of that tool. Two single pole Weldercontactors, each having a separate operating coil and connected oneineach side of the welding transformer primary are used, although it isobvious that a double pole contactor having a single operating coil maybe used with equal facility without changing the wiring connections asthe operating coils of the single pole contacts are connected inparallel. The welding cycle is divided into four periods correspondingto a delay period to permit the pressure to be built up within thewelding tool upon the welding electrodes, a weld period during whichcurrent is passed through the work between the electrodes, a hold periodin which the current is turned off but the pressure maintained upon theelectrodes and an o period in which thepressure on the electrodes isreleased. It is, of course, to be understood that while the system hasbeen shown in its most detailed form for the pneumatically operatedWelder, it can obviously be applied with simplifications to mechanicaland hand operated electric welding machines with the same welding cycleor a simplified cycle omitting either or both q of the hold and delayperiods, depending upon the particular type of machine used and therequirements of the welding.

'I'he internall wiring diagram of the panel is shown in Figure but willbe explained hereinafter with reference to the schematic simpliiledcontrol diagram of Figure 6. The panel wiring of Figure 5 terminates in10 terminals designated as pairs of terminals 63, 64, 65, 86 and 81.'I'he terminals 63 are line terminals to which the power line isconnected. The terminals 64 are connected to the welding contactoroperating coils. The terminals 65 are connected to the check i valveoperating coil.

The terminals 56 are connected to the operating coil for the operatingvalve of the pneumatically operating welding tool. The terminals 61 areconnected to an operating push button. In the simplified diagram ofFigure 6 the motor 31 is split up to include the series wound iield 68connected in series with the rheostat 4I and an armature 69 adjustablyconnected across the register 4I. 1I designates the operating pushbutton. 1 designates the operating coil of the control relay 5. 12designates the operating coil for the valve in the pneumaticallyoperated welding tool which supplies pressure to the welding electrodes.13 and 1H represent the operating coils of contactors 15 and l16 in eachside of the welding transformer primary. The Welding transformer isdesignated at 11 and the welding electrodes are schematically shown at18. The operating coil for the airline check valve is shown at 1Q.

The operation of the Welder control system will now be described. Therheostat 4I is adjusted to give the desired speed of operation and thecontact blocks 4 and 45 are adjusted in position to give the desiredweld and o periods respectively. By adjusting the contact supportingblock 44 upwardly a shorter weld" time is obtained and by adjusting thecontact supporting block 45 downwardly a shorter off period is obtained.The differential or spacing diierence between the blocks 44 and 45 willdetermine the delay andhold periods which will, of course, be uniform ifa uniform cam is used. For differential in these two periods variableshaped cams may be used to secure a predominance of delay time or apredominance of hold time as desired, these cams being substituted forthe cam 35. To initiate a series of welds the push button 1l is closed,thus placing the motor 31 across the line and initiating its operation.The rod I2 will then begin tov move as the motor accelerates its speed.As long as the bridging Contact I5 remains open the welding cycle is notinitiated but when the contact iii bridges its corresponding stationarycontacts upon the extreme lower movement of the rod IE, energization ofthe control relay operating coil 1 is momentarily effected and the`control relay closes, maintaining itself through bridging contact I3and the control relay contacts 9. The bridging contact IS is soregulated 'with relation to its cooperating stationary contacts as to beclosed only during the extreme lower movement ci the rod l2 and thebridging contact I3 is regulated with respect to its cooperatingstationary contacts as to be open only during the extreme lower movementof the contact bar I2. The duration of the opening of contact I3 isdesired to be coincident with or not appreciably greater than theclosing of bridging contact l so that once the control relay Ii has beenoperated the bridging contact I3 will be closed so as to have themaintaining circuit regardless of opening of the Vpush button 1I. Thebridging contact I6 is bypassed by control relay contact II but thecircuit for the operating coil 1 of the control relay 5 will not bemaintained Aif the push button-1I is open unless bridging Contact I3 isclosed. As-

' suming now that contact I6 is closed,energizing the cooperating coil1, the control relay 5I closes its contacts 8, 9 and II.l Bridgingcontact I3 is also closed at this time so even if push button 1I is letup one complete welding cycle will be pervalve and opens airlinepressure to the welding tool operating valve. As the rod I2 movesupwardly the bridging contact I5 engages its cooperating stationarycontacts and energizes the welding tool check valve operating coil 12vthrough the control relay contact 9. As the rod I2 continues to moveupwardly bridging contact I4l closes its cooperating stationary contactsand welding contactors 15 and 16 which close passing current through thework between the welding electrodes 18. The rod I2 continues to moveupwardly until it passes the highest point on the cam 35 and then in itsdownward direction first separates the contact I4 which deenergizes thewelder contact operating coils and interrupts the current through thework and in its continued downward movement separates the bridgingcontact I5 which deenergizes the check valve on the welding tool andrelieves the pressure on the welding electrodes. if the push button 1Ihas not been held down the rod moves downwardly until bridging contactI3 is open which opens the holding circuit through the operating coil 1of the control relay 5 and drops out the control relay, thusdeenergizing the entire. system. it is to be noted that when pushYbutton il is released immediately after closing of the control relay,the control relay is maintained through its contact 9 and bridgingcontact I3 and that the motor circuit is completed through control relaycontacts 9 and II and bridging contact I3. If the control push button 1Iis maintained in depressed position the system will continue to makesuccessive welds in the manner described until .the push button isreleased and bridging contact I3 opened.

It is to be particularly noted in the Welder control system disclosedthat energization of the system to initiate a welding cycle isdetermined by closing of the control relay ii and this can be effectedonly when the bridging contact I6 is closed, which occurs only in theoil period of the cycle and which is preferably oa relatively shortperiod in the extreme lower position of the operating rod I2. With thissystem it is impossible to energize the welding cycle at any pointexcept in the off period which is a necessary feature of operation as itwould obviously be un.n desirable to energize the system, for instance,when the Welder contacter controlcontact I6 were closed without.allowing for a delay period to eect building up of pressure on thewelding electrodes. If the push button ll should be closed while theoperating rod is in a position where bridging contact I6 is open eitherin the upward or downward direction, the rod IE will continue in itsmotion. without energizing the system until the bridging contact l@ isvclosed, whereupon the control relay is energized and the welding cycleinitiated. Using an operating motor for the timer having highacceleration, it is possible that even in the worst possible case wherethe rod I2 is in a position where the bridging contact I6 is closed withthe motor stopped so that the control relay is immediately energized, ithas been found that the motor builds up in speed fairly well during thedelay period so that the Weld period is not undesirably long for mostclasses of operation, even in the first weld. 'Y

Where extreme accuracy inthe rst weld is desired the motor 31 may beconnected to the line and brought up the speed before the push button isoperated to initiate the weld. This lenergizes the operating coils 13and 14S for the would necessitate simply placing the push button 1|, inFigure 6, in the circuit leading from the right hand side of thetransformer l to thecontact set including bridging contact l0 ratherthan in the circuit including the motor, which arrangement has beenshown in the partial diagram of Figure 7, where an additional switch l@is provided for connecting and disconnecting the motor as desired. Withthis operating arrangement the switch 19 is closed to initiate motoroperation and thereafter closing of the push button li will effectinitiation of the Welding'cycle without the necessity of bringing themotor up to speed. Again, however, regardless of the position of the rodI2 when push button 1l is depressed, the control relay will not beenergized to energize the welding control system until the rod [I2 hasreached a position at which bridging contact l@ is closed so that, ineach case, the control system is energized at the olf period of thecycle.

The arrangement shown partially in Figure 'l is adapted for use not onlywith the type of motor particularly described but also with asynchronous motor utilizing any conventional type of variable speedtransmission .to secure variations in the operating speed of the Weldingtool. This arrangement secures not only extremely accurate timing butalso permits the expansion of the system to include the synchronizationof the operation of the Welding contactors to the preferred point on thevoltage wave of the supply source.

Figure 9 illustrates a conventional type of welding machine indiagrammatic form to which the control system of the present inventionmay be applied. This includes a frame |0| which sup- |03 connected to amovable electrode |04. A.

cooperating electrode |05 is mounted on the lower part of the frame andinsulated therefrom by an insulating sleeve |06. Leads |01 are connectedto the secondary of the welding transformer to energize the electrodes|04 and |05. A uid pressure inlet |08 is indicated for connection to anysuitable source of fluid pressure, preferably coinpressed air, which isused to actuate the piston |03 within the cylinder |02. The valve isshown in the frame |0| and includes a movable valve portion |09/ adaptedto be moved by the solenoid coil 12. The position of the partsillustrated in Figure 9 is at the conclusion of a hold time in which thecoil 12 has just been deenergized to move the valve portion |09downwardly and connect the inlet port on the under side of the piston|03 with the source of fluid pressure. 'Ihe `force is now exertedtending to move the upper electrode to separated position into thedotted line position of the piston as shown. To move the electrode toapply pressure to the work the coil 12 is energized moving the valveportion |09 While certain preferred embodiments' of the] invention havebeen specifically disclosed, itis understood `that the invention is notlimited thereto as many variations will be'readily apparent to thoseskilled in the art and the invention is to be given its broadestpossible interpretation Within the terms of the following claims.

V What is claimed is:

aimes? l. In a Welder control system for electrically welding work bypassing current therethrough between electrodes pressed against thework, a motor driven contact making and breaking member, anelectromagnetic contactor for controlling the passage of current throughthe work, an energizing circuit for said contactor including said motordriven contacts, means for initiating a welding cycle, and means forpreventing energization of said contactor by said motor driven contactsuntil after the motor driven member has passed through a positioncorresponding to the off period in the Welding cycle after actuation ofsaid initiating means.

2. Ina Welder control system for electrically welding work by passingcurrent therethrough between electrodes pressed against the work, aplurality of sets of contacts, motor driven means for operating saidcontacts, an electromagnetic contactor controlling the passage ofcurrent through the work, an energizing circuit for said contactorincluding therein one set of said c0- operating contacts and thecontacts of an auxiliary relay, means for initiating a welding cycle,another set of said cooperating contacts controlling the energization ofsaid auxiliary relay when said initiating means is actuated to effectclosing of the relay contacts to place the energizing circuit of thecontactor under the control of the rst mentioned set of cooperatingcontacts, said another set of contacts functioning to energize saidrelay only in a predetermined period in the welding cycle.

3. In a welder control system for electrically Welding Work by passingcurrent therethrough between electrodes pressed against the Work, aplurality of sets of cooperating contacts, motor driven means foroperating said contacts, an electromagnetic contactor for controllingthe passage of current through the work, an energizing circuit for saidcontactor including one set of said cooperating contacts and thecontacts of an auxiliary relay, means for initiating a welding cycle,another set of said cooperating lcontacts controlling the energizationof said auxiliary relay when the initiating means is actuated andlimiting energization thereof to a period wherein the rst mentioned setof contacts is open. v

4. In a Welder control system for electrically f Welding work by passingcurrent therethrough between electrodes pressed against the work byfluid pressure, a plurality of sets of cooperating contacts, a motordriven member, for operating said contacts in cyclic arrangement,electro- I welding work by passing current therethrough betweenelectrodes pressed against the work by fluid pressure, a plurality ofsets of cooperating contacts, a motor driven member for operating saidcontacts in cyclic arrangement, electromagnetically operated valve meanscontrolling the application of fluid pressure to said electrodes, anelectromagnetic contacter controlling the passage of current through thework, an auxiliary relay, an energizing circuit for said valve meansincluding one set of said cooperating contacts and contacts of saidrelay, an energizing circuit for said contactor including another set ofsaid cooperating contacts and contacts of said relay, means forinitiating a welding cycle, and a third set of said cooperating contactscontrolling the energization of said relay and limiting energizationthereof to the off period in the welding cycle, a fourth set of saidcooperating contacts forming a maintaining circuit for .said auxiliaryrelay to insure rformance of a full welding cycle independent ci theinitiating means and the third set or cooperating contacts.

6. In a Welder control system for electrically welding Work by passingcurrent therethrough between electrodes pressed against the Work by duidpressure, a plurality ol sets of cooperating contacts, motor drivenmeans for effecting operation of said contacts, electromagneticallyoperated valve means controlling the application of fluid pressure tosaid electrodes, an electromagnetic contactor for controlling passage ocurrent through the Work, an auxiliary relay, an energizing circuit ofsaid valve means including one set of cooperating contacts and cori-ltacts of said relay, an energizing circuit for said contacter includinga second set of cooperating contacts and contacts of said relay, meansfor initiating the Welding cycle including means for connecting saidmotor to the line and ior ciecting energization of said auxiliary relay,and a third set of said cooperating contacts in the energizing circuitof said relay whereby complete closing of the energizing circuit of therelay can be effective only in the on period in the Welding cycle.

7. In a Welder control system for electrically welding Work by passingcurrent therethrough between electrodes pressed against the Worlr byfluid pressure, a plurality of sets of cooperating contacts, motordriven means for effecting operation of said contacts,electromagnetically operated valve means controlling the application oiduid pressure to said electrodes, an electromagnetic contactor forcontrolling passage of current through the 'worin an auxiliary relay, anenergizing circuit for said valve means including one set of cooperatingcontacts and contacts of said relay, an energizing circuit for saidcontactor including a second set of cooperating contacts and contacts ofsaid relay, means for initiatlng the welding cycle including means forimmediately connecting the motor to the line to initiate drivingmovement thereof regardless of the cyclic position of the sets ofcooperating contacts, said initiating means also closing at one pointthe energizing circuit of said relay, and a third set of saidcooperating contacts located in said energizing circuit and adapted tobe closed only in the off period of the Welding cycle, whereby,regardless of the cyclic position of the contacts when the initiatingmeans is operated, the system will not become energized to effectcontrol of the valve means and contactor by Vthe motor driven sets ofcontacts until the off period in the Welding cycle is reached.

8. In a Welder control system for electrically Welding Work bypassingcurrent therethrough between electrodes pressed -against the Work by uidpressure, a plurality of sets of cooperating contacts, motor drivenmeans for operating said contacts in a predetermined cycle, means foreffecting relatively continuous operation of said motor independently oithe Welding operation, electromagnetically operated valve meanscontrolling the application of iluid pressure of said electrodes, anelectromagnetic contacter for controlling passage of current through theWork, an auxiliary relay, an energizing circuit for said valve meansincluding one set of cooperating contacts and contacts of said relay, an`energizing circuit for said contacter including another set of saidcooperating contacts and contacts of said relay, and an energizingcircuit for said auxiliary relay including a third set of saidcooperating contacts and means for initiating a Welding operation,whereby upon actuation of said initiating means the control system isnot energized until said last mentioned set of cooperating contacts isclosed, whereupon the auxiliary relay is energized and energization ofthe Valve means and contacter placed under the control oi said tWo irstmentioned sets of cooperating contacts. I v

9. Ina Welder control system for electrically Welding Worlr by passingcurrent therethrough between electrodes pressed against the Work by'duid pressure, a plurality of sets of cooperating contacts, motor drivenmeans for operating said contacts in a predetermined cycle, means foreffecting relatively continuous operation of said motor independently cithe Welding operation, electromagnetically operated valve meanscontrolling the application of uid pressure to said electrodes, anelectromagnetic contactor for controlling passage of current through theWork, an auxiliary relay, an energizing circuit for said valve meansincluding one set of cooperating contacts and contacts oi said relay, anenergizing circuit for said contacter including another set of saidcooperating contacts and contacts of said relay, an energizing circuitfor said auxiliary relay including a third set of cooperating contactsand means for initiating a Welding operation, a fourth set ofcooperating contacts forming a holding circuit for said auxiliary relayand permitting deenergization thereof only at the oi period in theWelding cycle, whereby, regardless of Where the initiating means isopened, the system Will not be deenergized until the complete cycle isperformed.

l0. In a Welder control system for electrically welding Work by passingcurrent therethrough between electrodes pressed against the Work by duidpressure, motor driven control means for effecting the operations in theWelding cycle in predetermined relation, means for controlling theapplication or duid pressure to said electrodes, an electric contactorcontrolling the passage of current through the Work, said motor drivenmeans being normally inoperative to effectv operation of the last twomentioned means, and auxiliary means under the control of said motordriven means and. actuable only in' the oi period of the Welding cyclefor placing the control of said fluid pressure controlling means andcurrent controlling means under the motor driven means to perform theWelding operation.

ll. In a Welder control system for electrically Welding work by passingcurrent therethrough between electrodes pressed against the work byfluid pressure, a plurality of sets of cooperating contacts,reciprocable means for effecting cyclic operation of said contacts,motor driven cam means for effecting reciprocation of said reciprocablemeans, electromagnetically operated valve means controlling theapplication of iiuid pressure to said electrodes, an electromagneticcontactor controlling the passage of current through the Work,sequentially operated sets of said contacts controlling respectively theenergization of said Valve means and of said electromagnetic contactor,the differential between the periods of operation of said setsdetermining the delay time in the Welding cycle for building up uidpressure and the hold time for maintaining uid pressure after theWelding current is interrupted, and means for regulating the speed ofmovement of said reciprocable means in its oppositedirections to eiect apredominance o hold or delay times in the Welding cycle as desired.

12. In a Welder control system for electrically Welding Work by passingcurrent therethrough between electrodes pressed against the Work byfluid pressure, a plurality of sets of cooperating contacts, a motordriven member for operating said contacts, electromagnetically operatedvalve means controlling the application of fluid pres- Welding Work bypassing current therethrough between electrodes pressed against the Workby fluid pressure, a plurality of sets of cooperating contacts, a motordriven member for operating said contacts, electromagnetically operatedvalve means controlling the application of uid presatraen? sure to saidelectrodes, an electromagnetic contactor controlling the passage ofcurrent through the Work, certain of said sets of contacts controllingthe energization of said valve means and of said contactor, normallyopen contacts in the energizing ,circuits between said certain sets ofcontacts, Valve means and contactor, one set of said rst mentionedcontacts eiecting closure of l said normally open contacts to energizethe system, said last mentioned set lceing timed for operation only in apredetermined part of the Welding cycle, another set of said firstmentioned contacts eiecting opening of said normally open contacts atthe completion of the welding operation to deenergize the system. J

i4. lin a Welder control system for electricallyv Welding Work bypassing current therethrough between electrodes pressed against theWork, motor driven contact making and breaking means for controlling thepassage of current motor driven contact making and breaking means forcontrolling the passage of current through the Work, auxiliary contactsin series with said motor driven contact making and breaking means,means for initiating a welding cycle, and means effecting closing ofsaidvauxiliary contacts and operable only in the off period of theWelding cycle after actuating said initiating means to place the controlof the welding current in said motor driven contact making and breakingmeans.

FRANK H. ROBY.

